The present invention pertains to circular power saws of the type having tungsten carbide teeth spaced thereabout.
Conventional saws of the present type as used in sawmills comprise a circular steel disk several inches in diameter having tungsten carbide teeth spaced about the saw perimeter with the major axis of each tooth in chordal relationship with the circular saw body. A frontal face of the tooth is parallel to said axis. In rip saws that cut with the grain of the wood the hook or rake angle of the teeth, i.e., the included angle defined by a blade radius and the tooth frontal face, is normally between twenty and thirty degrees. Increasing the tooth hook or rake angle while advantageous to saw blade efficiency reduces the mass of the saw shoulder, that area of the blade rearward of the tooth, to the extent that the shoulder is weakened and rendered susceptible to fatigue and fracturing.
U.S. Pat. No. 4,135,421 discloses a circular saw having elongate hardened tooth inserts wherein one end of the insert constitutes the front face in distinction to conventional saw tooth placement wherein an inclined lengthwise face of the tooth constitutes the frontal face. The saw blade of the above mentioned patent has closely spaced teeth suitable for a cut-off type saw with each tooth projecting forwardly over a dimpled outer blade area constituting a gullet. The gullets formed by webs of reduced thickness are intended to minimize noise resulting from conventional open saw blade gullets. The hook or rake angle of the tooth frontal face appears to be less than ten degrees angularity. Further, the tooth major axis is inclined at about 75 degrees to a blade radius intersecting the tooth outermost edge. Still further, no provision is made or advantages discussed for accentuating the tooth rake or hook angle.
While a desirable increase in rake angle is possible with an insert type tooth as seen in U.S. Pat. No. 3,372,719 such teeth are extremely costly to manufacture and maintain and for the most part are no longer widely used in sawmills partially for the reason the same cut a wide, and hence wasteful, kerf. U.S. Pat. No,. 3,730,038 is of interest for the reason a somewhat similar saw shoulder is disclosed.